碳钢连铸坯凝固过程溶质再分配及宏观偏析的研究

Solute redistribution and macrosegregation in continuous casting carbon steel slab during solidification process

基于溶质再分配修正的谢尔(Scheil)模型,计算并分析了凝固参数、钢水流动、合金成分等对碳钢连铸坯凝固过程溶质宏观偏析的影响,探讨了电磁搅拌条件下“白亮带”偏析的形成机理,并提出一些控制中心偏析的实际对策。结果表明,修正的谢尔模型可以很好地应用于铸坯宏观偏析的预测与分析中;凝固界面前沿钢水流动速度与凝固速度的比值vx/R对线状偏析、V型偏析、“白亮带”偏析等的形成有着决定性影响,选择足够的末端冷却、合理的电磁搅拌是抑制宏观偏析的有效途径;采用溶质富集层特征距离的概念,可显著简化碳钢各元素在固液界面处的溶质再分配计算。

Based on the modified Scheil model of solute redistribution,the effects of solidification parameters,molten steel flow and alloy composition on solute macrosegregation during solidification of carbon steel continuous casting billet were calculated and analyzed,the formation mechanism of “white band” segregation under the condition of electromagnetic stirring was discussed,and some practical countermeasures to restrain the central segregation were suggested. The main results were that:The modified Scheil model could be applied to predict and analyze the macrosegregation of casting slab rather well. The ratio v x/R of flow velocity of molten steel at the front of solidification interface to solidification velocity had a decisive influence on the formations of linear segregation,V-shaped segregation and “white band” segregation,etc. It was an effective way to select sufficient terminal cooling and reasonable electromagnetic stirring to decrease macrosegregation of slab. The introduction of the concept of characteristic distance of solute enrichment layer could drastically simplify the calculation of solute redistribution at S/L interface of various elements in carbon steel.